In manufacturing flocked fabric it is conventional to deposit a layer of flock on an adhesive coated substrate and to emboss the surface of the flocked fabric during this process with selected designs. Conventionally, the embossing process may be achieved by one of several processes using specialized equipment for such purposes. Among these embossing processes is air embossing. In the air embossing process a substrate is coated with an adhesive. While the adhesive is still wet it is covered with a layer of flock fibers forming the flocked layer. The adhesive coated substrate with the flocked fibers is then carried beneath a stencil while the adhesive is not yet set. The stencil under which the assembly moves typically comprises an elongated cylinder having perforations arranged in a desired pattern to be formed in the flocked surface. This embossing stencil typically is rotated at the same speed as the flocked layer moves beneath it. Air introduced within this cylindrical stencil is directed downwardly through the perforations forming the pattern onto the upper surface of the flocked layer. By choosing a particular arrangement of perforations in the screen, and by the selective application of air flow through the perforations, air jets are directed downwardly from the stencil and onto the surface of the flocked fabric. Since the flocked fabric has not yet set in the adhesive, the stream of air changes the angle of or substantially flattens the flock fibers forming the flock in selected areas, thus forming a pattern as the stencil rotates and the flocked fabric moves.
A variety of prior art systems are available for performing air embossing of flocked fabrics. Many such systems are generally satisfactory for embossing designs onto an embossable surface of the fabric that do not require a significant level of fine detail. However, typical prior art systems suffer from a variety of shortcoming which limit their utility for producing finely detailed patterns, and which result in embossed pile fabrics that include embossed regions having undesirable artifacts and visually unappealing surface features. For example, air embossed pile fabrics produced with conventional air embossing equipment are typically not able to produce embossed features having a characteristic size that is very small, thus such equipment is not able to give the embossed fabric an appearance with a fine, detailed surface structure. In addition, typical prior art air embossing systems are not able to direct air towards the embossable surface of the fabric at a controlled, desirable angle (e.g. essentially perpendicular to the fabric surface), and, thus, they tend to produce embossed features having a blurred or imprecise transition region between the embossed features and the unembossed regions of the surface, which results in an associated lack of crispness and definition to the overall appearance of the embossed fabric.
In addition, typical prior art air embossing systems also tend to produce embossed fabrics having embossed features distributed across the width of the fabric that are not uniform in appearance across the width of the fabric. Also, typical prior art air embossing systems have a tendency to direct air towards the surface of the fabric in a direction diagonal to the fabric surface resulting in an embossed surface wherein the pile fibers have an overall directional lay with respect to the substrate, thus creating a distorted, unattractive appearance in the embossed surface, which appearance does not accurately reflect the pattern provided in the stencil used for embossing.
Also, typical prior art air embossing systems utilize embossing stencils which often, because of manufacturing defects/tolerances and/or damage during use, do not rotate “true” (i.e. the distance between the outer surface of the stencil and the rotational axis of the cylinder is not constant around the circumference of the stencil), but rather include a substantial degree of “run out”. “Run out” during rotation of many typical prior art air embossing stencils is caused by a deviation from a circular cross-sectional shape of the embossing stencil (taken in a plane perpendicular to its longitudinal axis) and/or a displacement of the rotational axis if the stencil with respect to the longitudinal centerline of the stencil. Such “run out” in prior art air embossing stencils during rotation causes a deviation in the minimum separation distance between the embossable surface of a fabric being embossed and the portion of the outer surface of the stencil adjacent to the embossable surface through which the air is directed during embossing. Such deviation tends to create undesired variation in the level of definition of the embossed pattern on the fabric surface, and can also cause undesirable artifacts in the embossed pattern due to contact of the embossable surface of the fabric with the outer surface of the cylinder during rotation, thus causing a crushing of the pile fibers of the fabric in such locations. The “run out” in many prior art air embossing stencils also limits the separation distance between the outer surface of the embossing cylinder and the embossable surface of the fabric that is achievable while avoiding artifacts due to contact of the fabric by the outer surface of the embossing stencil during operation.
Some aspects and embodiments of the present disclosure are directed to improved air embossing systems and methods and improved embossed fabrics produced using the systems and methods. The present disclosure describes a variety of air embossing systems utilizing improved air lances for directing air onto and through a patterned stencil of the system and/or including stencil stabilizers to reduce the “run out” in stencils and increase the uniformity of the distance separating the portion of the outer embossing surface of the stencil adjacent to the fabric from the embossable surface of the fabric during rotation. The improved air lances and embossing systems described herein are able, in many embodiments, to solve many of the above-mentioned short comings of prior art air embossing systems and to produce embossed fabrics having an unprecedented level of fine detail, crisp transition between unembossed and embossed regions, lack of undesired artifacts due to non-uniformity in the distance separating the portion of the stencil adjacent the fabric from the fabric during rotation, and uniformity of the pattern across the width of the embossed fabric.